Helio Castroneves is certain of two things as he prepares for Sunday's Honda Grand Prix of St. Petersburg (Fla.) as a two-time defending champion: How to win the Indy Racing League event, and knowing none of his experience on the 1.8-mile waterfront street course necessarily will lead to winning again.

That a driver in seventh place can generate buzz about winning it all confirms that the NHRA has created more excitement with its inaugural Countdown to the Championship. While drivers praise the concept for that, they curse the unintentional drama it has spawned because of the resulting stress.

Audi has dominated the 24 Hours of Le Mans two years running with its powerful diesel prototype, but in the American Le Mans Series, it regularly runs second to Team Penske's Porsche Spyder. Both sides are fighting the rule book going into this weekend's Petit Le Mans at Road Atlanta.

Audi won the 24 Hours of Le Mans for the fourth straight year, overcoming the challenge of two Peugeot cars and wet conditions Sunday in the world's most famous endurance race. Frank Biela and Marco Werner of Germany and Emanuele Pirro of Italy drove diesel-powered Audi No. 1 to victory.

Seeking a record eighth 24 Hours of Le Mans victory, Tom Kristensen led after five hours of the world's most famous endurance race Saturday. After 67 laps, the Danish driver in the Audi No. 2 had a one-lap advantage over defending champion Marco Werner in the Audi No. 1, which was 19 seconds ahead of Stephane Sarrazin in Peugeot No. 8. A total of 54 cars started the 75th edition of Le Mans, which will end Sunday afternoon.